A power switch is a switch capable of transmitting a powerful current. A power switch may, for example, be connected between a power supply and an electric load and be operated so as to control the electrical current drawn by the load and thus, an instantaneous power of the load. An electric circuit may generally comprise both power lines and control lines. A power line may be distinguished from a control line in that it may be arranged to feed power to one or more electrical loads, whereas a control line (signal line) may be arranged for transmitting only very little power. Whether a given conductor is a power line or a control line may depend on the application in question. For instance, a power line in a microscopic or miniaturized device may have dimensions similar to a control line in a macroscopic device. A power line and a power switch may be defined, respectively, as a conductor and a switch connected or connectable in series with a load. A control line and a control switch may be defined as a conductor and a switch, respectively, which may be operated to control, e.g., a current through the load or a voltage across the load without being connected in series with the load.
A power switch may be turned on and off. Turning on may be defined as controlling the switch to pass from a nonconductive state into a conductive state. Turning off may be defined as controlling the switch to pass from a conductive state into a nonconductive state. When the switch is conductive, it is said to be on or closed. When the switch is nonconductive, it is said to be off or open.
A problem that may be encountered with operating a power switch is that of voltage spikes which may be generated by inductive elements in the circuit when the power switch is turned off. High voltages may thus be generated across the power switch or across other components of the circuit when the power switch is abruptly turned off. Such voltages may be detrimental to the circuit.